The battery pack is widely used as an electric power source of a mobile electric equipment, for example, such as a mobile phone. The battery pack has, for example, a structure assembling a flat prismatic shaped cell and an electric circuit board to aim at protection of the cell. In addition, for the purpose of a positioning of the circuit board corresponding to the cell and an undesired short circuit between the outer surface of the cell and the circuit board, for example, a board holder made of resin is inserted between the cell and the circuit board in the battery pack.
As mentioned above, the circuit board is set to the cell through the board holder, and in this state a cap or a label is set or stuck to the cell as the outer structure in the battery pack.